Panoramic Radiography

Question 1

in panoramic radiographs, the sensor swings _____

Answer 1

in front of the patient

Question 2

in panoramic radiographs, the x-ray source swings _____

Answer 2

behind the patient

Question 3

_______ are unique to panoramics

Answer 3

ghost artifacts

Question 4

for anterior teeth, the source must first go through the _____

Answer 4

spine

Question 5

for the Lt/Rt areas, the source must first go through the ____

Answer 5

opposite side (To get a right side image, source must travel first through the left)

Question 6

having the x-ray beam travel through Lt mandible to Rt mandible to sensor OR spine to anterior to sensor creates….

Answer 6

ghost artifacts

Question 7

ghost artifacts usually have the same _____ as the image that formed it

Answer 7

right-left orientation

Question 8

ghost artifacts are usually seen _____ than the object that forms the ghost

Answer 8

higher up on the radiographic image

Question 9

examples of ghost artifacts

Answer 9

• mandibular ramus
• screws
• earrings
• Pt positioned too far back
• spine

Question 10

common features of ghost artifacts (4)

Answer 10

• same general shape
• appear on opposite side of image
• positioned higher
• more blurred than real image

Question 11

the farther an object from the x-ray source/closer to the source, the more ____ and ______

Answer 11

magnified and more blurry

Question 12

the close an object to the x-ray sensory/the farther from the source, the more ____

Answer 12

minified

Question 13

minimized images/magnification can be used to identify _____

Answer 13

position errors

Question 14

anteriorly positioned

Answer 14

• anterior teeth horizontally minimized

- excess spine at sides of image

Question 15

posteriorly positioned

Answer 15

• anterior teeth horizontally magnified

- loss of TMJs off sides of image

Question 16

chin tipped down positioned

Answer 16

• excess arch smile
• excess distortion
• loss of TMJ off the top of image

Question 17

chin tipped up

Answer 17

• flat/inverted smile
• excess distortion
• superimposes palate on Mx teeth
• Can see loss of TMJ image

Question 18

rotation error/lateral displacement of midline

Answer 18

• teeth/ramus closer to the x-ray source are horizontally maginified
• teeth/ramus farther from source are horizontally minimized

Question 19

slumped spine artifact

Answer 19

creates broad opaque mandible

Question 20

bilateral oral airway artifacts

Answer 20

• impairs visualization of Mx apices

- tongue must stay up

Question 21

most common panoramic image error

Answer 21

oral airway artifact (where the patient doesn’t keep tongue up)

Question 22

swallowing artifact

Answer 22

• hyoid bone

- airway space

Question 23

movement vertically during exposure creates…

Answer 23

vertical movement (“band”) artifact

Question 24

movement horizontally results in…

Answer 24

duplication of structures or deletion of structures

Question 25

remove ____ for panoramic

Answer 25

• earrings/piercings
• glasses
• RPD
• dentures

Question 26

CBCT acquisition geometry

Answer 26

1. source/receptor rotate around patient
2. series of 2D projection images
3. computerized reconstruction of 3D info

Question 27

another word for 3D information/pixels

Answer 27

voxels

Question 28

CBCT is dimensionally ____, relatively _______ imaging of hard tissues

Answer 28

accurate, high resolution

Question 29

CBCT has good imaging of soft tissues/air interfaces, but poor ______

Answer 29

soft tissue differentiation (muscle vs fat vs fluid)

Question 30

CBCT has (more/less) information than a panoramic

Answer 30

more

Question 31

three ways to view CBCT

Answer 31

1. slicing
2. volume rendering
3. reconstructed radiographs

Question 32

CBCT scans: slices/section details

Answer 32

• most accurate
• most detailed
• when lost, use crosshairs
• dimensionally accurate

Question 33

most common view, standard anatomic planes axial/sagittal/coronal

Answer 33

multiplanar reformatted (MPR)

Question 34

convention for CBCT is viewing “____”

Answer 34

toes up

Question 35

CBCT scans: volume rendering details

Answer 35

• spatial relationship
• dimensionally accurate
• threshold settings significantly influence appearance of tissue
• NOT reliable to assess fine details or bone quality

Question 36

CBCT scans: reconstructed radiograph details

Answer 36

• not reliable for fine bone details
• great for quick overviews
• great for cephalometric analysis
• no spine image
• not dimensionally accurate

Question 37

do reconstructed panoramics have ghost artifacts?

Answer 37

no, they do not

Question 38

artifacts in CBCT

Answer 38

• patient motion

- metal streak

Question 39

any distortion or corruption of image information that misrepresents reality

Answer 39

image artifact

Question 40

patient motion artifacts (CBCT)

Answer 40

• double contours

- excessive double streaking

Question 41

how to limit patient motion artifacts

Answer 41

• patient education
• straps
• faster scan times

Question 42

CBCT artifact resulting from patient motion

Answer 42

patient motion artifact

Question 43

CBCT artifact resulting from x-ray’s inability to penetrate metal/other dense material

Answer 43

metal streak artifact

Question 44

metal streak artifacts (CBCT)

Answer 44

• combination of light/dark streaking artifacts surrounding dense objects
• usually confined to axial planes

Question 45

how to limit metal streak artifacts

Answer 45

remove what metal you can

Question 46

3 types of field of view

Answer 46

small, medium, large

Question 47

small FOV gets…

Answer 47

teeth (dental)

Question 48

medium FOV gets..

Answer 48

dentoalveolar

Question 49

large FOV gets…

Answer 49

maxillofacial

Question 50

voxels range

Answer 50

0.5mm to less than 0.1mm

Question 51

the smaller the FOV, the ____ the allowed voxel size

Answer 51

smaller